Various arrangements have heretofore been used for securing elastomeric parts to metal portions of motor vehicles. One such arrangement is found in the U.S. Pat. No. 4,792,475 issued Dec. 20, 1988 to Alfred A. Bien entitled Composite Joint Pad For Synthetic Resin Panels. The '475 patent discloses a mounting arrangement and method of manufacture for clamping synthetic resin panels to a workpiece such as a vehicle metal substructure. A composite joint pad has a plate-like metal bushing pre-molded therein. The bushing comprises a raised central embossment having an exposed portion terminating in an arcuate sectioned rim extremity positioned a predetermined distance outwardly from the bonding face of the pad. Upon the bushing exposed embossment being received in a panel aperture, the pad's face is bonded to a panel mating surface with the rim flush with an adjacent surrounding surface of the panel. As a result, the pad's arcuate sectioned rim is clamped to the substructure by means of a threaded fastener being overdriven in the bushing stem without causing stress on the panel.
The U.S. Pat. No. 4,592,937 issued June 3, 1986 to Nagata et al. entitled Arcuate Side Molding discloses an arcuate resin plate side molding of a vehicle adapted to be attached to a curved surface of an automobile metal body avoiding holes being formed therein. The thermal expansion coefficient of the side molding is different from that of the automobile body. Therefore, the direct attachment of the molding to the metal body results in thermal deformation of the molding relative to the body, for example, in a hot day in summer. In the Nagata et al. patent the molding comprises a resin plate having projections formed in the backside thereof, and an intermediate member provided with slots for receiving the projections of the resin plate. In assembling the resin plate and the intermediate member, the projections are inserted through the slots of the intermediate member, and then the tips of the projections are heat caulked to join the intermediate member to the resin plate. In this way the resin plate and the intermediate member are longitudinally slidable relative to each other.
The U.S. Pat. No. 4,597,153 issued July 1, 1986 and U.S. Pat. No. 4,529,244 issued July 16, 1985 to common inventor W. S. Zaydel disclose a method for mounting a plastic body panel on a vehicle underlying metal substructure together with the mounting structure therefore. The Zaydel patents disclose a fastener fixedly attaching one end portion of the plastic panel on the metal structure. A mounting block is slidably mounted on the metal substructure longitudinally spaced from the fastener to define a path of longitudinal movement of the mounting block toward and away from the fixed end portion of the plastic panel. A spring urges the mounting block to a certain longitudinal position and is yieldable to permit movement of the mounting block away from the certain longitudinal position. A fastener attaches the plastic panel to the mounting block so that the plastic panel is effectively supported in a manner enabling longitudinal movement relative to the fixed one end portion to accommodate thermal or hygroscopic growth of the plastic panel.
The U.S. Pat. No. 3,875,661 issued Apr. 8, 1975 to Lindstrom et al. discloses a flexible subassembly for installation on a vehicle body. The Lindstrom subassembly includes a flexible elastomeric panel having a peripheral contour corresponding to a similar peripheral contour on the body, a plurality of square bosses on a mounting surface of the flexible panel, a rigid reinforcing panel disposed in juxtaposition with the mounting surface, and a plurality of apertures in the reinforcing panel corresponding to the bosses. Each aperture is larger than the corresponding boss in a direction parallel to the peripheral contour so that thermal expansion and contraction of the flexible panel is directed along the peripheral contour thereby to assure a continuous contour across the interface between the flexible panel and the body.
Referring now to the drawings, FIG. 1 depicts a fragmentary vehicle body frame 10 showing a prior art arrangement for mounting a metal fender 12' on a substructure frame portion 14'. The fender 12' is formed with an integral inwardly extending mounting flange 16', having a plurality of attachment holes 18' therein. The fender 12' is adapted for locating on the substructure portion 14' with the holes 18' aligned with attaching holes 20' in the substructure portion 14' for reception of suitable threaded fasteners 22'. Various other fasteners 24' and clips 26' are shown for use in securing other portions of the fender 12' to the vehicle substructure frame 10.
An example of one prior art fastening arrangement for securing a plastic panel member to a metal substructure is shown in FIGS. 14 and 15 of the drawings. FIG. 15 discloses a plastic panel "a" mounted on a metal substructure such as sheet metal flange "b" by a fastening arrangement generally indicated at "c". It will be seen in FIG. 14 that the plastic panel "a" has an elongated slot "d" formed therein adapted for alignment with a circular opening "e" provided in the flange "-b". The fastening arrangement "c" comprises a threaded self-tapping or self-drilling screw including a threaded stem "f" having an enlarged shoulder portion "g" sized for guided longitudinal travel in the slot "d". A resilient spring washer "h" includes a ring portion "i" in flush contact with the outer surface of the plastic panel "a" and a plurality of radial spring tabs angled axially away from the plane of the ring portion "j" with their free ends engaging the underside of head "k" of the screw. The spring washer "h" provides an axial clamping force to maintain the plastic panel "a" in flush contact with the metal flange "b" while the slot "d" allows the plastic panel to slide relative to the flange to accommodate thermal growth of the plastic panel.
One disadvantage of the prior art mounting structure shown in FIGS. 14 and 15 concerns scraping or marking of the exposed surface "1" of the plastic panel by the ring portion "i" of the spring washer "h" as the plastic panel "a" moves relative to the fixed screw and washer. Such marking or scratching of the surface "1" is particularly undesirable in the automotive industry where the panel "a" is an fender, for example, and the surface "1" is a painted area exposed to view. Such a mounting structure results in the painted surface "1" being marred and damaged by the ring "i" during movement of the plastic panel. Another disadvantage of the prior art mounting structure of FIGS. 14 and 15 is the variable clamping force applied by the self-drilling screw may result in an excessive force restricting the sliding movement of the plastic panel "a" relative to the metal flange "b".